Conventionally, a technology that is mounted in a vehicle and performs various types of driving assistance for the vehicle is known. In PTL 1, a technology is proposed in which, while a vehicle is traveling at a constant speed, when an intention of the driver of the vehicle to change traffic lanes is confirmed, a preset vehicle speed set to allow the vehicle to travel at the constant speed is corrected towards a higher side and increased. As a result, lane change in time with the flow of traffic is performed.